1. Field of the Invention
The present invention relates to fibrous structures having a durable fragrance, particularly, textile fabrics, knitted goods and apparel provided with a durable fragrance by adhering microcapsules containing fragrances or essences thereto, and a process for preparing the same.
2. Description of the Prior Art
As regards fibrous structures such as apparel or the like having fragrance, various articles have been heretofore developed and many have been placed on the market. However, most of them have been such articles that are prepared by applying, for example, by spraying or coating, a fragrant material, such as perfume or the like, together with a binder or size, onto final products in the course of finishing, under an open atmospheric system, or by enveloping fragrant paper in packages when packing or by enclosing paddings, made of fragrant paper to transfer its scent to the textile fabrics, knitted goods or apparel.
However, needless to say fragrant fibrous structures, such as apparel obtained by a method as mentioned above, have been poor in durability of fragrance and very low in commercial value as the fragrance entirely vanishes by only one washing. Moreover, there have been even some cases where the fragrance can remain for no more than a few hours after wearing of the fibrous structures as the perfumes or essences instantaneously evaporate if once the fibrous, structures are brought into contact with the ambient atmosphere when they are worn. Further, with regard to the transfer of scent from the fragrant paper or paddings to the apparel, etc. in packages, there have been experienced some cases where the imparted scent varies in intensity in accordance with the lapse of time after sealing of the packages, consequently not presenting a pleasant scent so that the article itself becomes defective.
In order to eliminate such problems, an attempt has been made to apply a fragrant substance in a closed system, namely, as encapsulated in microcapsules, onto fibrous structures and then to convert the closed system to an open system by rupture of the microcapsules owing to stresses applied thereto to emit fragrance during using of the fibrous structures. For example, there have been proposals, such as a method of applying a mixture of microcapsules encapsulating a liquid toilet preparation with a sizing bath containing a melamine resin to a fabric (British Patent Specification No. 1,401,143); a method of adhering microcapsules encapsulating a perfume with the aid of a capsule remover mainly comprising a cationic organic substance such as quaternary ammonium salts or the like and a nonionic organic substance such as sorbitan esters or the like (Japanese Patent Application Laid-open No. 52-31,200); a method for preparing fragrant towel fabrics by applying a liquid mixture of microcapsules containing a perfume with an acrylic resin to a towel fabric (Japanese Patent Application Laid-open No. 58-4,886); a method for preparing printed fabrics emitting fragrance by printing a printing paste compounded with a thermoplastic material, a thickening agent and microcapsules having a starch envelope membrane encapsulating a perfume (Japanese Patent Application Laid-open Nos. 53-47,440 and 53-49,200); a method for preparing printed fabrics emitting fragrance by thermo-transfer printing a binder layer comprising a pigment, high molecular resin, microcapsules of a perfume, etc. to a fabric (Japanese Patent Application Laid-open No. 53-106,885); etc.
However, in such hitherto proposed methods wherein microcapsules are applied with a size or resinous binder to textile fabrics or knitted goods, drying or heating at relatively a low temperature yields a poor adhesiveness of the binders, resulting in a poor resistance to washing. Alternatively, whereas heat-fixing at a high temperature after drying improves the adhesiveness, it has shortcomings such that denaturing of perfumes or collapsing of microcapsules caused by vaporization of perfumes occurs due to the high temperature as well as the hand of the fabrics becomes stiff due to infiltration into the fabrics of the resin. Particularly in sheer woven or knitted fabrics, such as women's hosiery, the component yarns consist of nylon filaments with a smooth surface so that it is very difficult to adhere the microcapsules sufficiently. If a large quantity of binder is applied in an attempt only to increase an adhesion amount, the hand also becomes so stiff as to impair the commercial value of the fabrics.
Further, adhesion by a thermotransfer printing as disclosed in Japanese Patent Application Laid-open No. 53-106,885 cannot provide a sufficiently durable fragrance and, moreover, perfumes generally evaporated or denatured at 150.degree. C. or more present a problem such that perfumes that are durable in the thermotransfer printing are limited.
Furthermore, important problems encountered in most of those prior art techniques are that the materials employed for the sizes or binders, particularly, most of the nitrogen containing organic compounds, tend to spoil the fragrance due to their inherent unpleasant scents.